JP2015166631A - Process for filling gas storage container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and quickly fill a gas storage container with a gas mixture.SOLUTION: A gas storage container, such as a gas cylinder, is filled with a gas mixture comprising a first gas and a second gas under pressure by: filling the gas storage container with a liquid-solid mixture comprising liquefied first gas and solidified second gas; closing the gas storage container to the passage of gas into or out of the container; and further making the liquefied first gas and the solidified second gas gaseous within the closed gas storage container. The process is easier and more energy efficient than direct compression processes, and is safer and results in less wastage than direct liquid injection processes.

Description

  The present invention relates to a method for filling a storage container with a mixture of two or more gases. A gas storage container is generally a gas cylinder that stores and / or distributes a gas mixture, usually under high pressure, for example at a pressure of at least 10 MPa (100 bar).

  The gas mixture may be made by mixing the individual gases in appropriate proportions on site. However, it may be more convenient to use a premixed gas mixture stored in a container at high pressure.

  Examples of gas mixtures used daily include beer from a pressurized metal barrel such as a welding gas such as an argon / carbon dioxide / oxygen mixture, a “beer” gas, ie a nitrogen / carbon dioxide mixture, for example. Gas used in pubs and bars to help distribute food, anesthetic gases such as oxygen / nitrous oxide mixtures, and fire extinguishing gases such as nitrogen / carbon dioxide mixtures.

  For example, a gas cylinder holding a gas mixture under a high pressure of 10 MPa (100 bar) or more can be prepared by simply pumping the gas mixture into the cylinder using a gas compressor. Such filling methods tend to be used in the field where fewer cylinders are filled.

  An example of a gas cylinder that is filled using a gas compressor is a diving compressed air cylinder that is prepared using a diving air compressor to compress the air and send it to the cylinder.

  Patent Document 1 (US Pat. No. 5,826,632 (published in October 1998)) discloses a method of filling a gas storage container with a gas mixture. This method provides a uniformly mixed gas flow under pressure, monitors the flow rate and composition of the mixture, and adjusts the flow rate and / or composition as necessary to provide a predetermined ratio of gases in the gas mixture. Including maintaining. The gas mixture is then fed to one or more gas cylinders. US Pat. No. 5,826,632 illustrates the provision of a gas cylinder containing 90% argon and 10% carbon dioxide at 18.2 MPa (182 bar).

  A gas cylinder containing the gas mixture under high pressure can also be provided by sequentially feeding each component of the gas mixture into the cylinder. The method includes either measuring the increase in partial pressure in the cylinder (manometer method) or measuring the increase in the mass of the cylinder during the addition of each component (gravimetric method).

  The manometer method is inaccurate, especially in the case of non-ideal gases, and may typically involve the use of different types of pressure gauges for low and high pressures. Changing the pressure gauge in this manner takes time and increases the time required for cylinder filling. Furthermore, such pressure gauges are generally expensive.

  Gravimetric methods are usually more accurate than manometer methods. However, this method still requires expensive equipment and can be quite complicated.

  Patent Document 2 (US Pat. No. 5,427,160 (published in June 1995)) discloses a method of filling a gas storage container with a combustible mixed gas. The method preferably includes directing combustible gas under pressure from the first intermediate vessel to the gas storage vessel, and then directing oxidant gas under pressure from the second intermediate vessel to the gas storage vessel. Yes. The gas flow to the storage vessel is controlled by appropriate valves and pressure transducers. This Patent Document 2 (US Pat. No. 5,427,160) is intended for use in a vehicle airbag device, and includes air (including oxygen in the air acting as an oxidant gas) and hydrogen as a combustible gas. It is illustrated that a gas storage container containing a mixture consisting of at a pressure of 17.2 MPa (2,500 psi (˜172 bar)) is prepared.

  One drawback of the method involving sequential addition of components of the gas mixture is that the gas in the cylinder may stratify until the gas mixture reaches equilibrium. Such stratification may be overcome by feeding light components to the bottom of the cylinder using a mixing tube or rotating the cylinder in a filled state. Another option is to fill the cylinder with the desired amount of gas in order of increasing gas density. US Pat. No. 5,353,848 (published October 1994) discloses such a method.

  A serious drawback of the direct compression method is that each cylinder is controlled at a slow rate, for example, less than 0.1 MPa (1 bar) / second, in order to control and / or minimize the heating of the cylinder by adiabatic compression of the gas. It must be filled. Filling the cylinder with the gas mixture can take 1-2 hours, so filling is one of the rate limiting steps in preparing a high pressure gas cylinder. In addition, a significant amount of energy is required to compress the gas to a pressure sufficient to fill the cylinder. Furthermore, the capital and operating costs of high pressure compressors are generally expensive.

  A further disadvantage of the direct compression method is that the heat of compression can have a significant adverse effect on the metering accuracy required to monitor the gas flow into the cylinder. Obviously, this effect is undesirable because the composition of the gas mixture is generally important.

Patent Document 4 (U.S. Patent Application Publication No. 2008/0202629 (published in August 2008)) is a method for producing a gas container containing a gas mixture under high pressure, and liquefying or cooling while cooling the gas container. A two-stage method is disclosed that includes a step of supplying a solidified first gas to a gas container and then a step of introducing a second gas into the gas container before closing the gas container. After closing, the container can be warmed to ambient temperature, and the liquefied or solidified first gas becomes gaseous, thereby increasing the pressure in the container. The pressure inside the container at 15 ° C. may be from 25 MPa (250 bar) to 130 MPa (1300 bar). This method is particularly useful for producing high pressure gas containers for airbag systems that include pure gases such as argon, oxygen, nitrogen, hydrogen, helium, dinitrogen monoxide (N ₂ O), or mixtures thereof. It is disclosed that it is advantageous if the first gas is argon and the second gas is helium. Patent Document 4 (US Patent Application Publication No. 2008/0202629) discloses a method that enables precise metering of gas mixture components.

Certain cryogenic slurries consisting of solid CO ₂ and cryogenic liquids are known in the art. For example, US Pat. No. 3,393,152 (published July 1968) discloses a solid suspended in a cryogenic liquid having a boiling point of less than about −300 ° F. (−184 ° C.). A refrigerant composition comprising carbon dioxide particles is disclosed. A preferred low-temperature liquid is liquid nitrogen, but it is disclosed that liquid air or liquid argon can also be used. The proportion of solid carbon dioxide in the composition may be 5% by weight to 95% by weight, but a proportion of about 40% by weight is preferred where high refrigeration capacity is required. Patent Document 6 (US Pat. No. 3,393,152) passes carbon dioxide gas compressed into liquid nitrogen in a pressure tank or expands liquid carbon dioxide to generate carbon dioxide snow. Is directly dropped onto liquid nitrogen to suspend carbon dioxide in liquid nitrogen to form the composition. It is disclosed herein that the composition is useful as a refrigerant and as a source of inert gas. The composition can also be used as a refrigerant, and as such can be used in various fields such as welding and blow molding.

  US Pat. No. 5,368,105 (published November 1994) discloses a cryogenic slurry for use as a fire extinguishing agent. The slurry has a mixture of particles of solid carbon dioxide suspended in liquid nitrogen at a ratio of about 1: 1 by weight.

  Patent Document 7 (International Publication No. 00/36351 (published in June 2000)) is a mixture of liquid nitrogen (or liquid air, for example, 50 to 90% by weight) and ethanol (for example, 20 to 60% by weight). A slurry containing solid carbon dioxide particles (e.g., 10 to 50 wt%) suspended in the water is disclosed. Here, it is disclosed that the composition can have a petrolatum or creamy consistency and can be used to treat warts, freeze seal pipelines, and cold laboratory samples. It has been done. WO 00/36351 also establishes the hypothesis that the mixture may be used in place of dry ice in many areas, and due to the good weight / cooling properties of the mixture itself, It suggests that it can be used to transport / store refrigerated / frozen foods such as food.

US Pat. No. 5,826,632 US Pat. No. 5,427,160 US Pat. No. 5,353,848 US Patent Application Publication No. 2008/0202629 US Pat. No. 3,393,152 US Pat. No. 5,368,105 International Publication No. 00/36351

  It is an object of a preferred embodiment of the present invention to provide a novel method for filling a gas storage container with a pressurized gas mixture, preferably while eliminating one or more of the disadvantages of the prior art. is there.

According to a first aspect of the present invention, in a method for filling a gas storage container with a gaseous mixture of at least a first gas and a second gas under pressure, the method comprises:
Filling a gas storage container with a liquid / solid mixture having a liquefied first gas and a solidified second gas;
Closing the gas storage container with respect to the passage of gas flowing into and out of the container;
Gasifying the liquefied first gas and the solidified second gas into the closed gas storage container;
A method for filling a gaseous mixture is provided.

  The inventors have observed that liquefied argon / solid carbon dioxide slurry does not boil as easily as liquefied argon itself when fed to a gas cylinder. Suppressing boiling during filling means that higher pressure filling is achievable or that lower pressure is required when injecting the slurry into the cylinder, unlike pure cryogenic liquids. . Furthermore, the loss of low temperature fluid during filling is reduced.

  Without being bound to any particular theory, the inventors believe that this observation occurs because of the specific heat capacity of solid carbon dioxide that provides additional refrigeration capacity. The inventors expect that similar boiling suppression effects should be observed in other low temperature slurries containing different mixtures of liquefied and solidified gases such as liquid nitrogen / carbon dioxide.

  We also note that if there is solid carbon dioxide in the liquid / solid mixture, the solid carbon dioxide appears to suppress the immediate boiling of the liquefied first gas, and the mixture is liquefied first gas. It was observed that there was less “scattering” of the liquefied first gas during filling because it had a higher viscosity than alone.

  The term “under pressure” means that the gas mixture is at a pressure above atmospheric pressure, for example at a pressure of at least 4 MPa (40 bar). The container is typically suitable for storing and / or distributing gas up to a pressure of about 50 MPa (500 bar). Typically, the container is suitable for storing and distributing gas at a pressure of at least 10 MPa (100 bar), 20 MPa (200 bar), or at least 30 MPa (300 bar).

  The solid / liquid mixture is generally stable for at least 10 minutes, preferably at least 30 minutes, more preferably up to 1 hour, for example at an ambient pressure of about 0.1 MPa (1 bar) to about 0.2 MPa (2 bar). Yes. In this context, the term “stable” means that the mixture can be handled at ambient pressure without significant loss of one or more of its components.

  The solid / liquid mixture is usually a fluid that can be poured, pumped / piped along a conduit, and adjustable by a valve. Depending on the relative proportions of liquefied gas and solidified gas, the mixture's consistency and appearance will vary from a thick creamy substance (a substance not much different from whipped cream or white petrolatum) to a smooth milky substance. May be in the range. The viscosity range of the mixture may be from about 1,000 to about 10,000 cPs. Preferably, the mixture is composed of finely divided solid particles suspended in the liquid phase. A liquid / solid mixture may be described as a cryogenic slurry or slush.

  When the inventors have warmed the liquefied argon / solid carbon dioxide mixture to ambient temperature, the liquefied argon initially evaporates leaving a substantial amount of solid carbon dioxide, and then gradually sublimates. Observed to go. A homogeneously mixed argon / carbon dioxide mixture is formed by diffusion of the gas in the vessel. We expect other liquid / solid mixtures containing solid carbon dioxide to behave similarly.

  The relative proportions of liquid and solid components in the mixture are determined by the desired gas mixture and the desire to make the mixture more fluid. In a preferred embodiment, there are about 40% to about 99% by weight liquid component and about 1% to about 60% solid component by weight.

  The uniqueness of the first and second gases will be determined by the gas mixture filling the container. Examples of gas mixtures suitable for use with the present invention include welding gas, “beer” gas, anesthetic gas, and fire extinguishing gas.

  Suitable welding gases include nitrogen / carbon dioxide mixtures (eg, about 80% to about 95% nitrogen and about 5% to about 20% carbon dioxide) and argon / carbon dioxide mixtures ( For example, about 80% to about 95% argon and about 5% to about 20% carbon dioxide). In such a welding gas, a part of nitrogen or argon gas may be replaced with oxygen. Thus, the welding gas can contain 0 wt% to about 5 wt% oxygen.

  Particularly suitable welding gases include about 80% to about 90% by weight argon, 0% to about 5% oxygen, about 5% to about 20% carbon dioxide. Examples of suitable welding gases include about 2.5 wt% oxygen, about 7 wt% to about 20 wt% carbon dioxide, the remainder being argon (about 77.5 wt% to 90.5 wt% ).

  A suitable “beer” gas comprises a nitrogen / carbon dioxide mixture (eg, from about 40 wt% to about 70 wt% nitrogen and from about 30 wt% to about 60 wt% carbon dioxide).

  Suitable anesthetic gases include oxygen / nitrogen oxide mixtures (eg, about 65% to about 75% oxygen and about 25% to about 35% nitrous oxide).

  Suitable fire extinguishing gases include a nitrogen / carbon dioxide mixture (eg, a 1: 1 weight ratio).

  Therefore, the first gas may be selected from the group consisting of nitrogen, argon, and oxygen. Other suitable gases include helium, neon, xenon, krypton, and methane.

  The second gas usually stabilizes in a solid state at ambient pressure. In this context, the term “stable” means that the solid form of the second gas gasifies (sublimates) too rapidly at ambient pressure so that the solid form can be easily handled under these conditions. Or by melting / evaporation). In general, the second gas is selected from the group consisting of carbon dioxide and nitrous oxide.

  The liquid / solid mixture may be a binary mixture of liquefied gas and solidified gas. However, the liquid / solid mixture may be a mixture of a plurality of types of liquefied gas and one type of solidified gas, or may be a mixture of one type of liquefied gas and a plurality of types of solidified gas. In some preferred embodiments, the liquid / solid mixture includes a liquefied third gas. The liquefied third gas may be immiscible with the liquefied first gas, but in a preferred embodiment, the liquefied first gas and the third gas can be mixed together.

  In a preferred embodiment where the gas storage vessel is filled with welding gas, the liquefied first gas is liquid argon and the solidified second gas is solid carbon dioxide. In such embodiments, the liquid / solid mixture may also have liquid oxygen that is miscible with liquid argon. Thus, the liquid / solid mixture may have about 80 to about 90 wt% liquid argon, 0 to about 5 wt% liquid oxygen, about 5 to about 20 wt% solid carbon dioxide.

  The present invention can be applied to any type of container that stores and / or distributes pressurized gas, such as, for example, a gas tank or other gas storage container. A gas storage container usually forms an internal space for holding a pressurized gas mixture and has an outer cylinder with an opening for receiving a fluid flow control unit and a fluid that flows into and out of the outer cylinder. A fluid flow control unit installed in the opening for controlling the flow.

  The present invention has particular application to gas cylinders such as, for example, high pressure gas cylinders made from steel or aluminum. In some preferred embodiments, the container is a single gas cylinder. In another preferred embodiment, the container is a central “main” cylinder in gas communication parallel to a plurality of “secondary” cylinders in a multi-cylinder pack. In such an embodiment, the outer cylinder of the central cylinder is typically made from aluminum and the outer cylinder of each secondary cylinder is usually made from steel.

  The gas storage container may be a cylinder having an inner surface lined with a heat insulating material. A suitable example of such a cylinder is described in British Patent 2,277,370, the disclosure of which is incorporated herein by reference. Nevertheless, it is preferred that the gas storage container is not lined.

  The gas storage container is also at least one inner cylinder provided in the internal space, forming an internal space portion that holds the liquid / solid mixture in a spaced relationship with the outer cylinder, and the rest of the internal space The inner cylinder may be in fluid communication with the portion. Such a structure prevents embrittlement of the outer cylinder.

  In these embodiments, cryogenic fluid is supplied to the inner cylinder in the container. The vessel is then sealed and the cryogenic fluid is allowed to gasify, filling the vessel and any associated secondary vessel with pressurized gas. The inner cylinder not only isolates the cryogenic fluid from the outer wall of the container (and thereby prevents embrittlement of the container) but also reduces the boiling rate due to the tendency to thin, providing a more uniform boil-off.

  The inner cylinder is preferably in a “loose fitting” state, that is, preferably not fixed to the outer cylinder.

  Since the inner cylinder is exposed only to hydrostatic pressure, it is preferably “thinned”. The inner cylinder usually has a base portion and a surrounding wall that are sufficiently thick so that the inner cylinder itself can be supported when it contains a cryogenic liquid. The thickness of the base and the surrounding wall depends on the material forming the inner cylinder, but in general, the base and the wall of the inner cylinder are about 0.1 mm to about 10 mm in thickness, preferably about 0.25 mm to About 5 mm. For example, when the inner cylinder is made from a metal such as steel, aluminum, or nickel, the thickness of the base and the wall is generally not more than about 2 mm, for example, about 1 mm to about 2 mm. Further, when the inner cylinder is made from a polymer material such as silicon or polyester film, the thickness of the base or the wall is slightly increased, for example, less than about 5 mm, for example, about 1.5 mm to about 4 mm. .

  The inner cylinder is an “open top type” or “open end type” bucket, for example, a base and a surrounding wall that is substantially circular (although not necessarily) substantially perpendicular to the base. It is preferable that the container has The mouth of such an inner cylinder becomes an open end. In some embodiments, the open end of the bucket may be an inverted cone.

  The gas storage container preferably has at least one support for supporting the inner cylinder in a spaced relation to the outer cylinder. Any suitable support may be used, such as a spacer arm and / or leg for the inner cylinder, or a support base on which the inner cylinder is seated. The support may be fixed to the inner cylinder (although not necessarily so). The support is usually made from a cryogenic material and generally has a low heat transfer coefficient. Suitable materials include plastics and polymers, but packaging materials can also be used.

  The container may have a plurality of inner cylinders. For example, each inner cylinder may be a long thin pipe having a closed bottom end and an open upper end forming a mouth. Moreover, even if the diameter of the pipe is larger than the diameter of the opening of the outer cylinder (in that case, the pipe is introduced into the outer cylinder prior to housing), it is smaller than the diameter of the opening of the outer cylinder. (In this case, each pipe is inserted into the outer cylinder through its opening).

  In a preferred embodiment, the container has a single inner cylinder. In such an embodiment, the mouth of the inner cylinder preferably has a diameter larger than the diameter of the opening. The diameter of the mouth of the inner cylinder may be at least 100% larger than the diameter of the opening, preferably at least 200% larger, for example at least 400% larger. The diameter of the mouth of the inner cylinder may be a value up to about 99% of the inner diameter of the outer cylinder.

  The inner cylinder is usually self-supporting even when filled with a cryogenic fluid. The inner cylinder is rigid, i.e. self-supporting and may be resistant to deformation if possible. Alternatively, the inner cylinder or at least one inner cylinder may be deformable. In such an embodiment, the inner cylinder may be deformed, for example by rolling, folding or crushing, and then inserted into the container through the opening of the outer cylinder. The inner cylinder may then be expanded in the container using gas pressure or water pressure. In an embodiment in which the inner cylinder has elasticity, the inner cylinder returns to its original shape without helping a person inside the container. In this regard, the inner cylinder is made of an elastic material, or the inner cylinder has an essentially elastic or “spring loaded” frame to support the deformable sheet material that forms the base and walls of the container. Either.

  Because it is the subject of a cryogenic fluid filling, the inner cylinder is typically made from a material that is resistant to embrittlement at cryogenic temperatures where it will be exposed. Suitable materials include, for example, special metals such as aluminum and nickel, steels such as stainless steel, polymer materials such as silicon such as catalyst-curing silicon and polydimethylsiloxane, polyethylene terephthalate (PET and Mylar (registered trademark)) )), Polyethylene such as polytetrafluoroethylene (PTFE), and perfluorinated elastomer (PFE).

  The inner cylinder has at least one for providing an additional gas communication state between the inner space portion formed by the inner cylinder and the remaining portion of the inner space formed by the outer cylinder in addition to the mouth. May have an opening. In such a case, the opening is generally provided in the inner cylinder wall that is equal to or higher than the maximum height of the cryogenic fluid filled in the container. However, in a preferred embodiment, the mouth is preferably the only opening in the inner cylinder.

  The term “separated relationship” is used in the sense that it is located away from it or there is a gap between them. In other words, in the present invention, the outer cylinder is arranged away from the inner cylinder so that the low-temperature fluid filled in the inner cylinder is isolated from the outer cylinder by a gap between them. The gap is usually 1 mm or more, preferably 5 mm or more.

  The term “opening” is used to mean at least not completely closed. That is, in the present invention, the mouth is at least not completely closed with respect to the rest of the internal space, and is preferably completely open. In a preferred embodiment, the mouth is not directly attached to any part of the container, particularly the fluid flow control unit.

  The mouth of the inner cylinder is preferably in a spaced relationship with the fluid flow control unit.

  The interior space usually has an upper half and a lower half. The extent to which the inner cylinder extends into the lower or upper half of the interior space depends on the amount of cryogenic fluid to be filled into the inner cylinder. The inner cylinder may extend from the lower half of the internal space to the upper half. For example, in embodiments where the container is the central main cylinder of a multi-cylinder pack, the inner cylinder may basically extend from near the bottom of the interior space to the top, or up to 90% of the interior space length. However, in the embodiment in which the container is a single gas cylinder, the entire inner cylinder is preferably provided in the lower half or the lower third of the internal space.

  Certain preferred containers for storing and / or distributing pressurized gas are disclosed in pending European patent applications (numbers will be announced later) and identified under APCI Docket No. 07492 EPC, the disclosure of which Are incorporated herein by reference.

  In order to inhibit the diffusion of the second gas necessary for forming a gaseous mixture in which the bag is uniformly mixed, the present inventors have disclosed that the inner cylinder in the form of a bucket with an upper opening is a bag with a sealed mouth. I found out that it is better than the inner cylinder of the form. Furthermore, the inventors have observed that the use of an inner bucket at the base of the container avoids the violent convection encountered if the mixture is fed to an inner bag connected to a fluid flow control unit. . Furthermore, the inventors have observed that the inner bucket is more robust than the inner bag.

  The gas storage container or the inner cylinder provided therein may be filled with a liquid / solid mixture using a nozzle inserted into the passage through the fluid flow control unit. Generally, the nozzle has a first conduit structure that is supplied with cryogenic fluid and a second conduit structure that discharges expelled air and / or gaseous cryogenic fluid from the container when the container is filled with fluid. . The first conduit structure may be in the second conduit structure and is preferably coaxial with the second conduit structure. In embodiments where the inner cylinder is spaced from the fluid flow control unit, the nozzle typically extends through the fluid flow control unit up to the height of the inner cylinder mouth. In this way, the spray is captured from the wall of the inner cylinder from the end of the nozzle.

  The passage may be manually opened and closed using a pressure cap or the like, but in a preferred embodiment, the passage is located at the end of the passage inside the container and biased to the closed position by a spring. Provide a valve.

  The method may include removing the pressure cap to open the passage and then inserting a nozzle into the opened passage to supply cryogenic fluid into the container. Alternatively, the method may include opening the passage by inserting a nozzle and pushing the valve open against the spring with its nozzle end.

  A suitable nozzle mechanism is disclosed in pending European Patent Application No. 10 195 461.8 filed on December 16, 2010, the disclosure of which is incorporated herein by reference.

  The liquid / solid mixture can be generated by contacting the second gas with the liquefied first gas. The second gas may be gaseous, but is generally in the form of liquefied or solidified particles.

  The liquid / solid mixture can be formed by passing a second gas under pressure through a liquefied first gas in an insulated tank. The liquefied first gas cools the second gas and solidifies the second gas in the form of finely divided solid particles that are then dispersed within the liquefied first gas. A suitable example of such a method is described in US Pat. No. 3,393,152, the disclosure of which is hereby incorporated by reference.

  A liquid / solid mixture may also be formed by rapidly expanding a gas or liquid pressurized second gas stream and mixing the expanded stream with a liquefied first gas spray. it can. Suitable examples of such methods are described in US Pat. No. 5,368,105 and WO 00/36351, the disclosures of which are hereby incorporated by reference. We note that the nozzle for liquid carbon dioxide may be heated to avoid clogging with solid carbon dioxide.

  The inventors have produced a liquid argon / solid carbon dioxide mixture by discharging carbon dioxide from a cylinder containing carbon dioxide pressurized onto liquid argon. Upon discharge, the carbon dioxide liquefies / solidifies to form fine droplets / particles that then drop to the surface and are mixed with liquid argon. We have observed that the mixtures made by this method are not “milky” so that they are sufficiently stable to allow filling into a gas cylinder.

  Liquid / solid mixtures may be produced in bulk in a tank or in a continuous in-line process. The mixture may be weighed gravimetrically or using a flow meter such as a Coriolis flow meter.

  The amount of liquid / solid mixture supplied or filled into the gas storage container is calculated to provide the desired pressure gas mixture in the container when the mixture becomes a gas.

Where the gas storage container is filled with pressurized gas, the amount of cryogenic liquid to be filled in the inner cylinder is the ideal gas equation of state, i.e.
PV = nRT
(Where P: desired pressure of the gas in the vessel, V: volume of the vessel, n: number of moles of gas, R: gas constant, T: absolute temperature).

Once a specific container is selected, V and maximum P are known, as is R and atmospheric temperature. At that time, the value of n can be calculated by the following equation.
N = PV / RT

Thereafter, the number of moles n of the gas is converted to mass M in grams (g) by multiplying this by the molecular weight A.
M = nA

For real gas above 5 MPa (50 bar), for example, there is a correction to be added to this basic formula, which depends on the attraction and repulsion between molecules and the finite and different sizes of molecules. These corrections are given by
PV = nRTZ
Can be taken into account by including the factor Z, ie the "compressibility" of the gas.

  For many gases, there are lists over a wide range of pressures and temperatures, and for some gases there are complex approximations.

  The formula is used as needed to determine the amount of liquid / solid mixture consisting of the first liquefied gas and the second solidified gas required to fill the gas storage container with the pressurized gas mixture. May be.

  In batch processing, a predetermined amount may be weighed (eg, by gravimetry or volumetric analysis) and then filled into containers using, for example, a funnel or siphon. Alternatively, in a continuous process using a filling line, the flow of the liquid / solid mixture to the first container may be metered (eg, using a flow meter or by gravimetric or volumetric analysis), once in advance Once the determined amount has been filled into the first container, the flow is suspended, the first container is closed and removed from the line, and then the second container is ready for filling with the liquid / solid mixture. May move to a fixed position.

  Filling the inner cylinder of a single container with a cryogenic liquid / solid mixture usually takes no more than 1 minute, and in some cases may take as little as 10-20 seconds.

  Gas storage containers are generally allowed to stand at ambient temperature for at least sufficient time to allow the mixture to become gaseous or to diffuse and provide a homogeneously mixed gas mixture. . In this regard, the gas storage container may be allowed to stand for about 12 hours to a week to ensure complete diffusion. Diffusion may be enhanced or facilitated, for example, by moving the container on its side, for example by moving the cylinder horizontally or rolling the container.

  According to a second aspect of the invention, a liquid / solid mixture comprising liquid argon, liquid oxygen, solid carbon dioxide is provided. The liquid / solid mixture is preferably about 80 to about 90 wt% liquid argon, 0 wt% or more, such as about 0.1 wt% to about 5 wt% liquid oxygen, and about 5 to 20 wt% solids. Carbon dioxide. The preferred liquid / solid mixture consists essentially of these proportions of liquid argon, liquid oxygen, solid carbon dioxide.

  The following description relates to the presently preferred embodiment of the present invention, by way of example only, with reference to the accompanying drawings. First, the drawings will be described.

1 is a schematic cross-sectional view of an embodiment of a gas container according to the present invention. (I) an acceleration pressure curve over time of a gas cylinder having an inner bag filled with a cryogenic slurry formed from liquid argon and solid carbon dioxide, and (ii) temperature change over time at different points of the cylinder, respectively. It is the shown graph.

  Referring to FIG. 1, the gas cylinder 2 has an outer cylinder 4 that forms an internal space 6 into which pressurized gas is placed. The outer cylinder 4 is made of steel and has an opening 8 that receives a fluid flow control unit 10 for controlling the flow of fluid into and out of the cylinder 2. The fluid flow control unit 10 comprises a filling inlet 12 with a pressure cap 14 suitable for filling a cylinder with a liquid / solid mixture comprising a liquefied first gas and a solidified second gas, and a customer outlet 16 having a control valve 18. And have. The fluid flow control unit 10 also has a pressure relief valve 20.

  The entire inner cylinder 22 made of aluminum is provided in the lower half of the inner space 6. The inner cylinder 22 forms an inner space portion 24 for holding the cryogenic fluid 26 in a spaced relationship with the outer cylinder. The support 28 creates a spaced relationship between the inner cylinder 22 and the outer cylinder 4. The inner cylinder 22 has an opening 30 for receiving a liquid / solid mixture from the fluid flow control unit 10 via an aluminum conduit 32 or dip tube. The end 34 of the conduit 32 extends below the mouth 30 of the inner cylinder 22 to ensure that the spray from the conduit 32 is captured by the inner cylinder 22. The end 34 of the conduit 32 is usually below the mouth 30 of the inner cylinder 22 so that the end of the conduit is positioned below the surface of the liquid / solid mixture 26 after the inner cylinder 22 is filled with the mixture. It does not extend.

  The opening 30 opens with respect to the remaining portion of the internal space 6, so that fluid communication is established between the inner cylinder 22 and the remaining portion of the internal space 6.

  The cylinder 2 is filled by removing the pressure cap 14 and supplying a liquid / solid mixture under the conduit 32 toward the inside of the inner cylinder 22. The control valve 18 at the customer outlet 16 may be in an open state so that the replacement gas can be scattered from the cylinder 2.

  The amount of liquid / solid mixture supplied to the cylinder 2, for example, the volume and mass, is based on the target gas pressure in the cylinder (thus, the volume of the cylinder, each density of the liquefied first gas and the solidified second gas and the mixture). The cylinder feed is metered to ensure that the correct amount of cryogenic fluid is added. Once the required amount of liquid / solid mixture has been added to the cylinder 2, the inlet 12 is closed by the pressure cap 14 and the control valve 18 at the customer outlet 16 is closed. The mixture is then gasified by evaporation and possibly sublimation, filling the cylinder 2 with a gas of the desired pressure.

EXAMPLE A 23.5 liter steel gas cylinder with a large neck (40 mm) was equipped with a fluid flow control unit with a cryogenic liquid fill and tube, a customer valve and a safety relief valve. A Mylar® bag was connected to the liquid filled tube and provided inside the cylinder. The resulting cylinder and interior were similar to those described in US Pat. No. 3,645,291.

  A slurry of 97 wt% liquid argon / 7 wt% solid carbon dioxide was prepared by spraying liquid carbon dioxide from a nozzle onto the surface of a liquid argon aeration tank. After a sufficient amount of carbon dioxide was added, the resulting slurry was confirmed for its free flow properties and color. An opaque white water-like liquid was obtained.

  The system was precooled by LIN before filling. After pre-cooling, about 4.2 liters of mixture (6 liters in total, including 1.8 liter loss due to blowback, dripping, etc.) was injected into the filling tube and bag through the central tube of the coaxial nozzle. When the mixture was injected, the customer valve was opened, and then both the customer valve and the liquid fill port were closed after the mixture was injected. The cylinder pressure and temperature were recorded over time. Carbon dioxide content was measured every few hours over several days until it returned to an equilibrium value of 7%.

The graph of FIG. 2 shows how the observed pressure in the cylinder increased over time as the LAr / CO ₂ slurry gasified. The pressure inside the cylinder increased rapidly in the first 30 seconds, mainly due to the evaporation of LAr from the slurry. After about 30 seconds, substantially all of LAr evaporated. The pressure continues to increase (albeit at a lower rate) due to the sublimation of solid CO ₂ from the slurry, even after the liquid argon has evaporated.

  The graph of FIG. 2 also shows that the temperature at the lowest temperature point (center) of the cylinder does not fall below -20 ° C. at any point during the filling process. These results show that cylinder cylinders can be made from materials such as steel that tend to be less durable to cryogenic temperatures.

  The inventors expect that the loss of the mixture due to blowback, dripping, etc. will be significantly reduced if the mixture is filled into an inner bucket in the base of the cylinder.

Advantages of preferred embodiments of the present invention include:
-Filling the gas storage container with the gas mixture is easier and faster compared to the direct compression method,
-Compared to the direct compression method, filling the gas storage container is more energy efficient,
・ Compared with direct liquid injection method, filling gas storage container is more reliable and safe, and ・ Less waste of liquefied gas when filling gas storage container,
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  The present invention is not limited to the detailed description given above with reference to the preferred embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention as defined in the claims. I want you to understand.

Claims (12)

In a method of filling a gas storage container with a gaseous mixture of at least a first gas and a second gas under pressure,
The method
Filling a gas storage container with a liquid solid mixture having a liquefied first gas and a solidified second gas;
Closing the gas storage container with respect to a gas passage flowing into and out of the gas storage container;
Gasifying the liquefied first gas and the solidified second gas into the closed gas storage container. The first gas is selected from the group consisting of nitrogen (N ₂ ), argon (Ar), oxygen (O ₂ ), helium, neon, krypton, methane, and mixtures thereof. The method according to 1. The second gas is carbon dioxide (CO ₂₎ and nitrous method according to claim 1 or claim 2, characterized in that it is selected from the group consisting of oxides of nitrogen (N ₂ o).   4. The liquid solid mixture of claim 1, wherein the liquid solid mixture has about 40 wt% to about 99 wt% liquid component and about 1 wt% to about 60 wt% solid component. The method described.   The method according to claim 1, wherein the liquid solid mixture comprises a liquefied third gas.   6. The method of claim 5, wherein the liquefied third gas is miscible with the liquefied first gas.   7. A method according to any one of the preceding claims, wherein the gaseous mixture is a welding gas.   The method according to claim 1, wherein the liquefied first gas is liquid argon, and the solidified second gas is solid carbon dioxide.   The method of claim 8, wherein the liquid solid mixture comprises liquid oxygen. The liquid solid mixture is
About 80 wt% to about 90 wt% liquid argon;
0% to about 5% by weight liquid oxygen;
10. A method according to claim 8 or claim 9 having from about 5 wt% to about 20 wt% solid carbon dioxide.   A liquid-solid mixture comprising liquid argon, liquid oxygen and solid carbon dioxide. About 80 to about 90 weight percent liquid argon;
Up to about 5% by weight liquid oxygen;
12. The liquid solid mixture of claim 11 having about 5 wt% to about 20 wt% solid carbon dioxide.

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